With the advancement of HTML5 technology, mobile web interactive advertisements based on HTML5 have offered users a superior experience. Drawing from Flow Theory, we constructed a research framework to elucidate how ‘flow’ influences user acceptance and sharing intentions towards H5 interactive advertisements. Furthermore, we aimed to identify factors influencing the flow experience of users. Given the Person-Artifact-Task (PAT) model, which frames the precursors to flow around three dimensions: person, tool, and task, this paper employs a model centered around the person, tool, and task. We categorized factors impacting flow experience into user factors and ad design factors. Adopting a quantitative research approach, we surveyed users of H5 interactive ads in China. Regression analysis was conducted using SPSS (version 26.0). Findings indicate: (1) Within user factors, Entertainment and Perceived Control, and within design factors, Interface Design Quality and Interactive Narrative, have a positive influence on flow. (2) Flow positively affects the acceptance and sharing willingness of users towards H5 interactive advertisements.